Eplontersen for Hereditary Transthyretin Amyloidosis With Polyneuropathy.

Importance: Transthyretin gene silencing is an emerging treatment strategy for hereditary transthyretin (ATTRv) amyloidosis. Objective: To evaluate eplontersen, an investigational ligand-conjugated antisense oligonucleotide, in ATTRv polyneuropathy. Design, Setting, and Participants: NEURO-TTRansform was an open-label, single-group, phase 3 trial conducted at 40 sites across 15 countries (December 2019-April 2023) in 168 adults with Coutinho stage 1 or 2 ATTRv polyneuropathy, Neuropathy Impairment Score 10-130, and a documented TTR variant. Patients treated with placebo from NEURO-TTR (NCT01737398; March 2013-November 2017), an inotersen trial with similar eligibility criteria and end points, served as a historical placebo ("placebo") group. Interventions: Subcutaneous eplontersen (45 mg every 4 weeks; n = 144); a small reference group received subcutaneous inotersen (300 mg weekly; n = 24); subcutaneous placebo weekly (in NEURO-TTR; n = 60). Main Outcomes and Measures: Primary efficacy end points at week 65/66 were changes from baseline in serum transthyretin concentration, modified Neuropathy Impairment Score +7 (mNIS+7) composite score (scoring range, -22.3 to 346.3; higher scores indicate poorer function), and Norfolk Quality of Life Questionnaire-Diabetic Neuropathy (Norfolk QoL-DN) total score (scoring range, -4 to 136; higher scores indicate poorer quality of life). Analyses of efficacy end points were based on a mixed-effects model with repeated measures adjusted by propensity score weights. Results: Among 144 eplontersen-treated patients (mean age, 53.0 years; 69% male), 136 (94.4%) completed week-66 follow-up; among 60 placebo patients (mean age, 59.5 years; 68% male), 52 (86.7%) completed week-66 follow-up. At week 65, adjusted mean percentage reduction in serum transthyretin was -81.7% with eplontersen and -11.2% with placebo (difference, -70.4% [95% CI, -75.2% to -65.7%]; P < .001). Adjusted mean change from baseline to week 66 was lower (better) with eplontersen vs placebo for mNIS+7 composite score (0.3 vs 25.1; difference, -24.8 [95% CI, -31.0 to -18.6; P < .001) and for Norfolk QoL-DN (-5.5 vs 14.2; difference, -19.7 [95% CI, -25.6 to -13.8]; P < .001). Adverse events by week 66 that led to study drug discontinuation occurred in 6 patients (4%) in the eplontersen group vs 2 (3%) in the placebo group. Through week 66, there were 2 deaths in the eplontersen group consistent with known disease-related sequelae (cardiac arrhythmia; intracerebral hemorrhage); there were no deaths in the placebo group. Conclusions and Relevance: In patients with ATTRv polyneuropathy, the eplontersen treatment group demonstrated changes consistent with significantly lowered serum transthyretin concentration, less neuropathy impairment, and better quality of life compared with a historical placebo. Trial Registration: ClinicalTrials.gov Identifier: NCT04136184; EU Clinical Trials Register: EudraCT 2019-001698-10.

Investigating KIF1A mutations in a Taiwanese cohort with hereditary spastic paraplegia.

BACKGROUND: Hereditary spastic paraplegia (HSP) is a heterogeneous group of inherited neurodegenerative disorders characterized by slowly progressive lower limbs spasticity and weakness. HSP type 30 (SPG30) is a HSP subtype caused by mutations in the kinesin family member 1A gene (KIF1A) and could be either autosomal dominantly or recessively inherited. The aim of this study was to investigate the clinical and genetic features of KIF1A mutations in a Taiwanese HSP cohort. METHODS: Mutational analysis of KIF1A was performed in 242 unrelated Taiwanese patients of Han Chinese ethnicity with clinically suspected HSP using targeted resequencing panel covering the entire coding regions of KIF1A. Clinical, electrophysiological and neuroimaging features of the HSP patients carrying a KIF1A mutation were characterized. RESULTS: Three different KIF1A mutations were identified in three patients with autosomal dominantly inherited HSP. Among them, KIF1A p.E19K was a novel mutation. The patient harboring KIF1A p.G321D presented with pure HSP, while the individuals carrying KIF1A p.E19K or p.R316Q manifested complex HSP with additional axonal sensorimotor polyneuropathy. The patients carrying KIF1A p.R316Q also had thoracic cord atrophy, thin corpus callosum and white matter hyperintensity. CONCLUSION: SPG30 accounts for 1.2% (3/242) of patients in the Taiwanese HSP cohort, suggesting that it is an uncommon HSP subtype in Taiwan. This study delineates the clinical and genetic features of SPG30 in Taiwan and provides useful information for the diagnosis and management of SPG30, especially in patients of Han Chinese descent.

Exploring steroid tapering in patients with neuromyelitis optica spectrum disorder treated with satralizumab in SAkuraSky: A case series.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) is a rare, chronic, autoimmune disease, characterized by astrocytopathic lesions in the central nervous system (Beekman et al., 2019; Fujihara et al., 2020). The main aim of NMOSD maintenance therapy is to reduce the frequency and severity of relapses and minimize future disability (Fujihara et al., 2020). Oral corticosteroids are used long-term to prevent relapses, but are associated with serious complications (Kessler et al., 2016; Kimbrough et al., 2012). In the SAkuraSky study, satralizumab reduced the risk of relapse in patients with NMOSD compared with placebo, with comparable rates of serious adverse events and infections between treatment arms (Yamamura et al., 2019). Here, we report on 16 patients who tapered their steroid dose during the openlabel extension (OLE) period of SAkuraSky. METHODS: SAkuraSky was a phase 3, multicenter, randomized, double-blind (DB), placebo-controlled study of satralizumab in combination with immunosuppressive therapies (ISTs) in patients with NMOSD. Patients were randomized 1:1 to receive 120 mg subcutaneous satralizumab or placebo in addition to a stable dose of their baseline IST. After completing the DB period or experiencing relapse, patients could enter the OLE period. In the OLE, all patients received satralizumab, and IST doses could be tapered at the investigator's discretion. We assessed the different steroid tapering patterns and their impact on relapse and safety. Patients were considered to have tapered their steroids if their steroid dose at the clinical cut-off date (CCOD: February 18, 2020) was lower than on the first day of the OLE. Annualized relapse rate (ARR) was calculated as the number of relapses divided by the total number of patientyears at risk. RESULTS: Overall, 36 patients receiving oral corticosteroids entered the OLE, of whom 16 tapered their steroid dose. The mean age (range) at baseline was 44.9 (16-73) years, all 16 were female, 14 (88%) were Japanese, and 15 (94%) were AQP4-IgG seropositive. None were receiving any additional ISTs. Patients tapered their steroids from a median of 10 (range: 5-25) mg/day at OLE baseline to 2.75 (0-15) mg/day at the CCOD. Three patients discontinued steroids entirely, and all three remained relapse free. One patient who remained relapse free had temporary increases in steroid dose. Three relapses were observed in two patients who tapered steroids during the OLE; all three relapses required treatment. One of the relapses occurred shortly after a drop in steroid dose from 25 to 10 mg/day. The ARR for steroid-tapered patients was numerically lower in the OLE period than the satralizumab group in the DB period. The safety profile of satralizumab was in line with the overall SAkuraSky population. Two serious infections were observed in steroid-tapered patients in the OLE, both in the same patient: one event (hepatitis E) occurred before the patient began tapering their steroid dose; and one event (influenza) occurred while the patient was tapering. CONCLUSION: During the OLE of SAkuraSky, 16 patients tapered steroids and the ARR did not increase from the DB period. Patient numbers limit interpretation.

Neuronal intranuclear inclusion disease in patients with adult-onset non-vascular leukoencephalopathy.

Neuronal intranuclear inclusion disease (NIID), caused by an expansion of GGC repeats in the 5'-untranslated region of NOTCH2NLC, is an important but underdiagnosed cause of adult-onset leukoencephalopathies. The present study aimed to investigate the prevalence, clinical spectrum and brain MRI characteristics of NIID in adult-onset nonvascular leukoencephalopathies and assess the diagnostic performance of neuroimaging features. One hundred and sixty-one unrelated Taiwanese patients with genetically undetermined nonvascular leukoencephalopathies were screened for the NOTCH2NLC GGC repeat expansions using fragment analysis, repeat-primed PCR, Southern blot analysis and/or nanopore sequencing with Cas9-mediated enrichment. Among them, 32 (19.9%) patients had an expanded NOTCH2NLC allele and were diagnosed with NIID. We enrolled another two affected family members from one patient for further analysis. The size of the expanded NOTCH2NLC GGC repeats in the 34 patients ranged from 73 to 323 repeats. Skin biopsies from five patients all showed eosinophilic, p62-positive intranuclear inclusions in the sweat gland cells and dermal adipocytes. Among the 34 NIID patients presenting with nonvascular leukoencephalopathies, the median age at symptom onset was 61 years (range, 41-78 years) and the initial presentations included cognitive decline (44.1%; 15/34), acute encephalitis-like episodes (32.4%; 11/34), limb weakness (11.8%; 4/34) and parkinsonism (11.8%; 4/34). Cognitive decline (64.7%; 22/34) and acute encephalitis-like episodes (55.9%; 19/34) were also the most common overall manifestations. Two-thirds of the patients had either bladder dysfunction or visual disturbance. Comparing the brain MRI features between the NIID patients and individuals with other undetermined leukoencephalopathies, corticomedullary junction curvilinear lesions on diffusion weighted images were the best biomarkers for diagnosing NIID with high specificity (98.4%) and sensitivity (88.2%). However, this diffusion weighted imaging abnormality was absent in 11.8% of the NIID patients. When only fluid-attenuated inversion recovery images were available, the presence of white matter hyperintensity lesions either in the paravermis or middle cerebellar peduncles also favoured the diagnosis of NIID with a specificity of 85.3% and sensitivity of 76.5%. Among the MRI scans of 10 patients, performed within 5 days of the onset of acute encephalitis-like episodes, five showed cortical hyperintense lesions on diffusion weighted images and two revealed focal brain oedema. In conclusion, NIID accounts for 19.9% (32/161) of patients with adult-onset genetically undiagnosed nonvascular leukoencephalopathies in Taiwan. Half of the NIID patients developed encephalitis-like episodes with restricted diffusion in the cortical regions on diffusion weighted images at the acute stage. Corticomedullary junction hyperintense lesions, white matter hyperintensities in the paravermis or middle cerebellar peduncles, bladder dysfunction and visual disturbance are useful hints to diagnosing NIID.

Treatment response, risk of relapse and clinical characteristics of Taiwanese patients with neuromyelitis optica spectrum disorder.

BACKGROUND/PURPOSE: The long-term disease course and efficacy of maintenance therapies have rarely been investigated in Asian patients with neuromyelitis optica spectrum disorder (NMOSD). METHODS: Medical records of patients fulfilling the 2015 International Consensus Diagnostic Criteria for NMOSD at three medical centers in Taiwan were systematically analyzed. Linear regression analysis was performed to investigate factors related to annualized relapse rate (ARR); survival analysis was used to estimate the relapse-free intervals among therapies. RESULTS: A total of 557 relapses affecting 648 regions (202 optic neuritis, 352 acute myelitis, and 94 brain syndromes) in 204 patients were analyzed during a follow-up period of 69.5 months (range, 1-420). Up to 36.1% of myelitis-onset patients and 24.0% of optic neuritis-onset patients exhibited a limited form disease, defined as having one or more relapses confined to the same region. The median ARR was significantly lower in patients with limited form disease than those with relapses involving multiple regions (0.30 vs. 0.47, respectively). An older age at disease onset was associated with a lower ARR (p = 0.023). Kaplan-Meier analysis showed that the estimated time (months) to next relapse was longest in rituximab-treatment group (58.0 ± 13.2), followed by immunosuppressant (48.5 ± 4.8) or prednisone (29.6 ± 4.6) groups, and shortest in those without maintenance therapy (27.6 ± 4.2) (p = 8.1 × 10-7). CONCLUSION: Limited form disease and older age at disease onset are associated with a lower relapse rate in NMOSD. Compared to no maintenance therapy, rituximab and immunosuppressant significantly reduce the relapse risks.

Diameter Reduction Determined Through Carotid Ultrasound Associated With Cardiovascular and All-Cause Mortality: A Single-Center Experience of 38 201 Consecutive Patients in Taiwan.

Background Few studies have evaluated the prognostic significance of diameter-based carotid sonographic measurements for mortality. We investigated whether a reduction in diameter of different carotid anatomical segments is associated with cardiovascular and all-cause mortality in a hospital-based cohort with universal health care. Methods and Results We conducted a retrospective cohort study of 38 201 patients who underwent carotid duplex ultrasound at a medical center in Taiwan. Carotid sonographic parameters were the diameter reduction percentage in carotid bifurcation, the internal carotid artery, the common carotid artery, and the external carotid artery and the overall carotid atherosclerotic burden score, determined by summing the scores from all segments. The vital status was ascertained by linking data to National Death Registry until 2017. During a median follow-up of 4.2 years, 5644 participants died, with 1719 deaths attributable to cardiovascular diseases. The multivariable-adjusted hazard ratios (HRs; 95% CIs) for cardiovascular mortality were 1.33 (1.16‒1.53), 1.58 (1.361.84), and 1.89 (1.58, 2.26) for participants with 30% to <40%, 40% to <50%, and ≥50% reduction in carotid bifurcation diameter, respectively, compared with participants with <30% diameter reduction (P for trend <0.001). The corresponding HRs (95% CIs) for all-cause mortality were 1.25 (1.16‒1.34), 1.42 (1.31‒1.54), and 1.60 (1.45‒1.77), respectively. Diameter reduction at other carotid sites and the carotid atherosclerotic burden score exhibited the same dose-response relationship. Conclusions This study suggests that reduction in carotid artery diameter, which can be determined through routinely available sonography, is an independent risk factor for all-cause and cardiovascular mortality.

Use of a Smartphone Application to Speed Up Interhospital Transfer of Acute Ischemic Stroke Patients for Thrombectomy.

Background: In most countries, large cerebral artery occlusion is identified as the leading cause of disability. In 2015, five large-scale clinical trials confirmed the benefit of intra-arterial thrombectomy. However, thrombectomy is a highly technical and facility-dependent procedure. Primary stroke centers need to transfer patients to comprehensive stroke centers to perform thrombectomy. The time-lapse during interhospital transfer would decrease the chance of the patient's proper recovery. Communication barriers also contribute to this delay. Aims: We used a smartphone application to overcome communication barriers between hospitals. We aimed to shorten the door-to-puncture time of interhospital transfer patients. Methods: We began using a smartphone application, "LINE," to facilitate interhospital communication on May 01, 2018. We carried out retrospective data analyses for all the transfer patients (n = 351), with the primary outcome being the door-to-puncture time in our comprehensive stroke center (China Medical University Hospital). We compared the three periods: May 01 to Dec 31, 2017 (before the use of the smartphone application); May 01 to Dec 31, 2018 (the 1st year of using the smartphone application); and May 01 to Dec 31, 2019 (the 2nd year of using the smartphone application). We also compared the transfer data with non-transfer thrombectomies in the same period. Results: We compared 2017, 2018, and 2019 data. The total number of transfer patients increased over the years: 63, 113, 175, respectively. The mean door-to-puncture time decreased significantly, going from 109, through 102, to 92 min. Meanwhile, the mean door-to-puncture time in non-transfer patients were 140.3, 122.1, and 129.3 min. The main reason of time saving was the change of the way of communication, from point-to-point interhospital communication to hub-to-spoke interhospital communication. Conclusions: We used this smartphone application to enhance interhospital communication, changed from the point-to-point to hub-to-spoke method. It made us overcome the communication barrier and build up interhospital connection, thus shortening the door-to-puncture time. Our experience demonstrated the importance of close communication and teamwork in hyperacute stroke care, especially in interhospital transfer for thrombectomy.

Intracerebral Hemorrhage in Cerebral Autosomal Dominant Arteriopathy With Subcortical Infarcts and Leukoencephalopathy: Prevalence, Clinical and Neuroimaging Features and Risk Factors.

BACKGROUND AND PURPOSE: Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a monogenic cerebral small vessel disease. The role of intracerebral hemorrhage (ICH) in CADASIL remains elusive. The present study aims to investigate the prevalence, characteristics, and risk factors for ICH in CADASIL. METHODS: This retrospective cross-sectional study investigated ICH and cerebral microbleeds (CMBs) in brain susceptibility-weighted imaging or T2*-weighted gradient-recalled echo images of 127 Taiwanese patients with genetically confirmed CADASIL. We analyzed CMBs, lacunes, white matter hyperintensity, and perivascular space. The total small vessel disease score (range, 0-4) was calculated to estimate the overall magnetic resonance imaging burden of small vessel disease. Multivariate regression analysis was performed to identify factors related to ICH lesions in CADASIL. RESULTS: Thirty-seven ICH lesions, including 15 symptomatic and 22 asymptomatic lesions, were found in 27 (21.3% [95% CI, 14.0%-30.9%]) of the 127 patients with CADASIL. The thalamus and lobar regions were the most common ICH locations, and 72.7% of the lobar hemorrhages occurred silently. Patients with CADASIL with ICH lesions more often had hypertension and a higher total small vessel disease score than those without ICH (odds ratio [95% CI]: 3.22 [1.25-8.30] and 3.79 [1.51-9.51]). The presence of CMBs in the brain stem and a total CMB count >10 were independently associated with ICH lesions in patients with CADASIL, with odds ratio (95% CI) of 5.82 (1.80-18.80) and 3.83 (1.08-13.67), respectively. CONCLUSIONS: ICH is an underestimated but important manifestation of CADASIL. The location and number of CMBs are associated with the presence of ICH lesions in patients with CADASIL.

Independent associations of urinary albumin-to-creatinine ratio and serum cystatin C with carotid intima-media thickness in community-living Taiwanese adults.

BACKGROUND: Renal function is a key factor of cardiovascular disease. Carotid intima-media thickness (IMT) has been widely used as a marker of early subclinical atherosclerosis. The determinants of cystatin C, a novel marker of renal function, have not been extensively studied in the Asian population. This study aimed to assess the determinants of cystatin C and explore whether carotid thickening was associated with urinary albumin-creatinine ratio and cystatin C in community-living Taiwanese adults. METHODS: A cross-sectional study was conducted on participants from Taichung City, Taiwan. All the participants underwent carotid ultrasonography. Carotid IMT-mean and IMT-maximum were derived. Kidney biomarkers were measured on the basis of urinary albumin-to-creatinine ratio (ACR) and cystatin C. Multiple linear regression analysis was used. RESULTS: A total of 1032 individuals were recruited, and 469 (45.44%) of them were men. An increased cystatin C level was significantly associated with older age, male gender, lack of physical activity, low HDL cholesterol, abdominal obesity, high hs-CRP, and high ACR. The multivariate-adjusted mean carotid IMT-mean and IMT-maximum values significantly increased by 80.49 and 195.23 µm for every one unit of increase in cystatin C level and by 0.07 and 0.14 µm for every one unit of increase in ACR, respectively (all p < 0.001 except ACR on IMT-maximum with p < 0.01). Lack of physical activity, low HDL, abdominal obesity, high hs-CRP, and high ACR were the determinants of cystatin C. CONCLUSION: Cystatin C and ACR were strongly and linearly associated with carotid thickening, a marker of subclinical atherosclerosis.

Subclinical Atherosclerosis Markers of Carotid Intima-Media Thickness, Carotid Plaques, Carotid Stenosis, and Mortality in Community-Dwelling Adults.

Carotid intima-media thickness (IMT), plaque, and stenosis are widely used as early surrogate markers of subclinical atherosclerosis and strong predictors of future deaths and cardiovascular events. Albuminuria is an indicator of generalized endothelial dysfunction that speeds up atherosclerosis. However, previous studies reporting these associations cannot rule out the confounding effect of albuminuria. We aimed to examine the independent and joint relationships between IMT markers and 10-year mortality in community-dwelling Taiwanese adults. This work was a community-based prospective cohort study consisting of 2956 adults aged at least 30 years recruited in 2007 and followed up through 2019. Cox proportional hazard regression models were used to examine associations of these subclinical atherosclerosis markers with mortality. During an average of 9.41 years of follow up, 242 deaths occurred. The mortality rate was 8.70 per 1000 person-years. Compared with those with carotid IMT less than 1.0 mm, persons with severely increased carotid IMT (≥2.0 mm) had an increased risk for death (hazard ratio (HR): 1.79; 95% confidence interval (CI): 1.07, 3.00). Compared with those without carotid plaque, persons with carotid plaque were more likely to have an increased risk for death (1.65; 1.21-2.32). Compared with those with carotid stenosis less than 25%, persons with carotid stenosis of 25-36% had a significant increased risk for death (1.57; 1.12-2.22). Considering these three IMT markers along with the traditional risk factors (c-statistic: 0.85) significantly increased their predictive ability of mortality compared with any individual variable's predictive ability (all p-values < 0.001 for comparisons of c-statistic values). Carotid IMT measures, including IMT thickness, carotid plaque, and carotid stenosis were significant independent predictors of mortality. Our study supports evidence of blood pressure-related media thickening markers to assess future mortality risks in Chinese adults of general population.

Mutation spectrum of Charcot-Marie-Tooth disease among the Han Chinese in Taiwan.

OBJECTIVE: Charcot-Marie-Tooth disease (CMT) is a clinically and genetically heterogeneous group of inherited neuropathies. Mutations in more than 90 genes have been implicated in CMT; however, the mutational spectrum of CMT in Chinese population remains obscure. This study aims to provide a comprehensive overview of the frequency of mutations in Taiwanese patients with CMT and look for genotype-phenotype correlations. METHODS: Mutational analyses were performed on 427 unrelated Taiwanese patients with CMT by polymorphic microsatellite markers analysis or real-time fluorescent PCR for PMP22 duplication, Sanger sequencing for GJB1 mutations, and targeted sequencing covering 124 genes causing or relevant to inherited neuropathies. We also correlated the genotypes with the phenotypic features, such as age at disease onset and ulnar motor nerve conduction velocity. RESULTS: Pathogenic mutations were identified in 312 patients (73.1%; 312/427), including 208 patients with a PMP22 duplication, 40 patients with a GJB1 mutation, and 64 patients with a mutation in one of other 18 CMT genes. A confirmed molecular diagnosis was achieved in 84.4% (266/315) of the patients with demyelinating CMT and 41.1% (46/112) of the patients with axonal CMT. Mutations in MPZ, MFN2, or NEFL are the most frequent disease causes in patients with infantile-onset CMT (≤2 years), while PMP22 duplications and mutations in GJB1, MFN2, or MPZ are the frequent causes among patients with childhood- or adolescence-onset CMT (3-9 years). INTERPRETATION: This study provides a genotype-phenotype landscape of CMT in Taiwan and highlights the unique spectrum of CMT genes frequencies among patients of Chinese origin.

Clinical and genetic profiles of hereditary transthyretin amyloidosis in Taiwan.

OBJECTIVE: The clinical and genetic profiles of hereditary transthyretin amyloidosis (ATTR) in Chinese populations remain elusive. We aim to characterize the features of ATTR in a Taiwanese cohort of Han Chinese descent. METHODS: Seventy-nine patients with molecularly confirmed ATTR from 57 Taiwanese families were identified by sequencing the transthyretin gene (TTR). The clinical and electrophysiological data were scrutinized. Cardiac involvement of ATTR was evaluated by echocardiography and cardiac scintigraphy. Four microsatellite and seven single-nucleotide polymorphism markers flanking TTR were genotyped to investigate the founder effect of the TTR Ala97Ser mutation. RESULTS: Most of the patients had a peripheral neuropathy with variable autonomic symptoms. The average age at disease onset (AO) was 58.2 ± 7.2 years, and the male patients had an earlier AO than female patients (56.6 ± 5.7 years vs. 61.8 ± 8.9 years, P = 0.013). Electrophysiological studies revealed a generalized axonal sensorimotor polyneuropathy and isolated median neuropathy in 84.5% and 15.5% of the patients, respectively. Up to 80% of the patients with ATTR had symptomatic or subclinical cardiac involvement. Six TTR mutations were identified in the participants including one novel mutation Glu89Asp. Among them, Ala97Ser was the most common mutation, accounting for 91.2% of the ATTR pedigrees. Detailed haplotype analyses demonstrated a shared haplotype in the 47 patients with the Ala97Ser mutation, suggesting a founder effect. INTERPRETATION: The present study delineates the distinct features of ATTR in Taiwan and provides useful information for the diagnosis and management of ATTR, especially in patients of Chinese descent.

Investigating CCNF mutations in a Taiwanese cohort with amyotrophic lateral sclerosis.

Mutations in the cyclin F gene (CCNF) have been recently identified in a small number of patients with amyotrophic lateral sclerosis (ALS) and/or frontotemporal dementia, and their role in patients with ALS in Taiwan remains elusive. The aim of this study was to elucidate the frequency and spectrum of CCNF mutations in a Taiwanese ALS cohort of Han Chinese origin. Mutational analyses of the CCNF gene were performed using Sanger sequencing in a cohort of 255 unrelated patients with ALS. Among these patients, the genetic diagnoses of 204 patients remained unclear after mutations in SOD1, C9ORF72, TARDBP, FUS, ATXN2, OPTN, VCP, UBQLN2, SQSTM1, PFN1, HNRNPA1, HNRNPA2B1, MATR3, CHCHD10, TUBA4A, and TKB1 had been investigated. Two novel heterozygous missense mutations in CCNF, p.S222P (c.664T>C) and p.S532R (c.1596C>T), were identified; 1 in each patient with apparently sporadic ALS. In vitro functional study demonstrated that both mutations result in a general and cyclin F-mediated ubiquitin-proteasome pathway dysfunction. The frequency of CCNF mutations in ALS patients in Taiwan is, therefore, approximately 0.8% (2/255). These findings expand the mutational spectrum of CCNF and also emphasize the pathogenic role of CCNF mutations in ALS.

Unmasking adrenoleukodystrophy in a cohort of cerebellar ataxia.

Adrenoleukodystrophy (ALD) is a rare and progressive neurogenetic disease that may manifest disparate symptoms. The present study aims at investigating the role of ataxic variant of ALD (AVALD) in patients with adult-onset cerebellar ataxia, as well as characterizing their clinical features that distinguish AVALD from other cerebellar ataxias. Mutations in the ATP binding cassette subfamily D member 1 gene (ABCD1) were ascertained in 516 unrelated patients with ataxia. The patients were categorized into three groups: molecularly unassigned hereditary ataxia (n = 118), sporadic ataxia with autonomic dysfunctions (n = 296), and sporadic ataxia without autonomic dysfunctions (n = 102). Brain MRIs were scrutinized for white matter hyperintensity (WMH) in the parieto-occipital lobes, frontal lobes, corticospinal tracts, pons, middle cerebellar peduncles and cerebellar hemispheres. Two ABCD1 mutations (p.S108L and p.P623fs) previously linked to cerebral ALD and adrenomyeloneuropathy but not AVALD were identified. ALD accounts for 0.85% (1/118) of the patients with molecularly unassigned hereditary ataxia and 0.34% (1/296) of the patients with sporadic ataxia with autonomic dysfunctions. WMH in the corticospinal tracts and WMH in the cerebellar hemispheres were strongly associated with AVALD rather than other ataxias. To conclude, ALD accounts for approximately 0.39% (2/516) of adult-onset cerebellar ataxias. This study expands the mutational spectrum of AVALD and underscores the importance of considering ALD as a potential etiology of cerebellar ataxia.

Clinical and biophysical characterization of 19 GJB1 mutations.

OBJECTIVE: Charcot-Marie-Tooth disease type X1 (CMTX1), which is caused by mutations in the gap junction (GJ) protein beta-1 gene (GJB1), is the second most common form of Charcot-Marie-Tooth disease (CMT). GJB1 encodes the GJ beta-1 protein (GJB1), which forms GJs within the myelin sheaths of peripheral nerves. The process by which GJB1 mutants cause neuropathy has not been fully elucidated. This study evaluated the biophysical characteristics of GJB1 mutants and their correlations with the clinical features of CMTX1 patients. METHODS: All patients with a validated GJB1 mutation were assessed using the Charcot-Marie-Tooth disease neuropathy score version 2 (CMTNS). The impacts of the mutations on the biophysical functions of GJB1 were characterized by assessing intracellular localization, expression patterns, and GJ Ca2+ permeability. RESULT: Nineteen GJB1 mutations were identified in 24 patients with a clinical diagnosis of CMT. Six are novel mutations: p.L6S, p.I20F, p.I101Rfs*8, p.F153L, p.R215P, and p.D278V. Diverse pathological effects of the mutations were demonstrated, including reduced GJB1 expression, intracellular mislocalization, and altered GJ functions. GJB1 mutations that caused a complete loss of GJ Ca2+ permeability appeared to be associated with an earlier disease onset, whereas those resulting in preservation of GJ permeability and with predominant cell membrane expression tended to have a later onset and a milder phenotype. INTERPRETATION: This study demonstrated that the degree of loss of GJ function caused by the GJB1 mutations might contribute to the onset and severity of neuropathic symptoms in CMTX1.

Spinocerebellar ataxia type 36 in the Han Chinese.

OBJECTIVE: To ascertain the genetic and clinical characteristics of the GGCCTG hexanucleotide repeat expansion in the nucleolar protein 56 gene (NOP56) in patients with spinocerebellar ataxia (SCA), sporadic ataxia, or amyotrophic lateral sclerosis (ALS) in Taiwan. METHODS: We conducted clinical and molecular genetic studies of 109 probands with molecularly unassigned SCA from 512 SCA pedigrees, 323 healthy controls, 502 patients with sporadic ataxia syndromes, and 144 patients with ALS. Repeat-primed PCR assays and PCR-fragment analysis for the number of short hexanucleotide repeats (<40 units) were performed to ascertain NOP56 hexanucleotide repeat expansion. Genotyping included 8 microsatellite markers and 17 single nucleotide polymorphisms flanking NOP56 and covering a region of 1.8 Mb to assess a possible founder effect. RESULTS: Eleven individuals from 3 SCA pedigrees have the NOP56 repeat expansions. The 3 pedigrees share a common haplotype spanning 5.3 kb flanking the NOP56 repeat expansions, suggesting a founder effect of spinocerebellar ataxia type 36 (SCA36) in the Han Chinese. The average age at symptom onset was 44.8 ± 3.8 years with truncal ataxia as the initial manifestation. Common features included slowly progressive truncal/limb ataxia, dysarthria, generalized hyperreflexia, and hearing impairment. Evidence of lower motor neuron involvement, including atrophy and fasciculation in the limb muscles and tongue, was mostly found in patients with prolonged disease duration. NOP56 repeat expansion was not detected in controls or patients with sporadic ataxic syndromes or ALS. CONCLUSIONS: SCA36 is an uncommon subtype, which accounted for 0.6% (3/512) of SCA cases in the Han Chinese population.

Characterization of CADASIL among the Han Chinese in Taiwan: Distinct Genotypic and Phenotypic Profiles.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is originally featured with a strong clustering of mutations in NOTCH3 exons 3-6 and leukoencephalopathy with frequent anterior temporal pole involvement. The present study aims at characterizing the genotypic and phenotypic profiles of CADASIL in Taiwan. One hundred and twelve patients with CADASIL from 95 families of Chinese descents in Taiwan were identified by Sanger sequencing of exons 2 to 24 of NOTCH3. Twenty different mutations in NOTCH3 were uncovered, including 3 novel ones, and R544C in exon 11 was the most common mutation, accounting for 70.5% of the pedigrees. Haplotype analyses were conducted in 14 families harboring NOTCH3 R544C mutation and demonstrated a common haplotype linked to NOTCH3 R544C at loci D19S929 and D19S411. Comparing with CADASIL in most Caucasian populations, CADASIL in Taiwan has several distinct features, including less frequent anterior temporal involvement, older age at symptom onset, higher incidence of intracerebral hemorrhage, and rarer occurrence of migraine. Subgroup analyses revealed that the R544C mutation is associated with lower frequency of anterior temporal involvement, later age at onset and higher frequency of cognitive dysfunction. In conclusion, the present study broadens the spectrum of NOTCH3 mutations and provides additional insights for the clinical and molecular characteristics of CADASIL patients of Han-Chinese descents.

Spinocerebellar ataxia 35: novel mutations in TGM6 with clinical and genetic characterization.

OBJECTIVE: To elucidate the clinical and cellular characteristics of spinocerebellar ataxia type 35 (SCA35), which is caused by mutations in the TGM6 gene encoding transglutaminase 6 (TG6), in a Taiwanese cohort. METHODS: Mutations in TGM6 were ascertained in 109 unrelated probands of Chinese descent with molecularly unassigned SCA from 512 pedigrees, in whom mutations responsible for 15 other ataxia syndromes had been excluded. The clinical features of all patients with a TGM6 mutation were systematically analyzed. The biological consequences of the newly identified TGM6 mutations were investigated in HEK293 cells transfected with mutant complementary DNA constructs. RESULTS: Two missense mutations (p.R111C and p.D510H) and one 3-base pair deletion (p.E574del) in TGM6 were identified. Among them, p.R111C and p.E574del were novel. The common features of SCA35 include a slowly progressive clinical course, trunk/limb ataxia, and hand tremors. The age at onset varies from adolescence to the fifth decade. Torticollis and intellectual impairment are rare manifestations. Brain MRI reveals diffuse cerebellar atrophy without involvement of the cerebral hemispheres or brainstem. The 3 mutations identified here attenuated the protein stability and catalytic activities of TG6. CONCLUSIONS: SCA35 is an uncommon ataxia syndrome, accounting for 0.6% (3/512) of SCAs among the Han-Chinese descent in Taiwan. This study broadens the mutational spectrum of SCA35 and stresses the importance of TG6 in cerebellar functions.

A novel TFG mutation causes Charcot-Marie-Tooth disease type 2 and impairs TFG function.

OBJECTIVE: To describe a novel mutation in TRK-fused gene (TFG) as a new cause of dominant axonal Charcot-Marie-Tooth disease (CMT) identified by exome sequencing and further characterized by in vitro functional studies. METHODS: Exome sequencing and linkage analysis were utilized to investigate a large Taiwanese family with a dominantly inherited adult-onset motor and sensory axonal neuropathy in which mutations in common CMT2-implicated genes had been previously excluded. Functional effects of the mutant gene products were investigated in vitro. RESULTS: Exome sequencing of 2 affected individuals in this family revealed a novel heterozygous mutation, c.806G>T (p.Gly269Val), in TFG that perfectly cosegregates with the CMT2 phenotype in all 27 family members. This mutation occurs at an evolutionarily conserved residue and is absent in the 1,140 ethnically matched control chromosomes. Genome-wide linkage study also supported its disease-causative role. Cell transfection studies showed that the TFG p.Gly269Val mutation increased the propensity of TFG proteins to form aggregates, resulting in sequestration of both mutant and wild-type TFG proteins and might thus deplete functional TFG molecules. The secreted Gaussia luciferase reporter assay demonstrated that inhibition of endogenous TFG compromised the protein secretion pathways, which could only be rescued by expressing wild-type TFG but not the p.Gly269Val altered proteins. TFG mutation was not found in 55 additional unrelated patients with CMT2, suggesting its rarity. CONCLUSION: This study identifies a new cause of dominant CMT2 and highlights the importance of TFG in the protein secretory pathways that are essential for proper functioning of the human peripheral nervous system.

Extensive molecular genetic survey of Taiwanese patients with amyotrophic lateral sclerosis.

Identification of genetic mutations has been of burgeoning importance in amyotrophic lateral sclerosis (ALS) in recent years. The aim of this study was to determine the frequency and spectrum of mutations in major ALS-causing genes in a Taiwanese ALS cohort of Han Chinese origin. Mutational analyses of the SOD1, TARDBP, FUS, OPTN, VCP, UBQLN2, SQSTM1, PFN1, HNRNPA1, and HNRNPA2B1 genes were carried out by direct sequencing in 161 unrelated patients with ALS, including 30 with familial ALS (FALS) and 131 with sporadic ALS (SALS). The CAG repeat size in ATXN2 and the GGGGCC repeat expansion in C9ORF72 of the patients were also investigated. Mutations were identified in 33 patients (20.5%, 33/161), including 22 with FALS and 11 with SALS. Mutations were identified most frequently in SOD1 (7.5%). Three mutations are novel, including SOD1 p.G10A, SOD1 p.D83N, and OPTN p.L494W. These findings broaden the spectrum of ALS-causing mutations and are indispensable for designing optimal strategies of mutational analysis and genetic counseling of ALS for patients of Chinese origin.